Catalytic oxidation of graphite

Hennig, G. R.

doi:10.1016/0022-1902(62)80258-9

Cited by 98 publications

(37 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The slope of the Brønsted-Evans-Polanyi relationship is a measure of the extent to which the transition state resembles the final state (complete rupture of the oxygen-catalyst bond). Figure 3 shows that the linear relationship has a slope of 0.35, indicating that the transition state, which Hennig [91] proposed to be a bridging metal-oxygen-carbon species, is closest to the initial state in character. Figure 4 outlines the possible steps of the reaction mechanism.…”

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 95%

“…This is presumably especially clear for the employed bulk gold sample, which has a very low surface area (1.1 m 2 /g). Small gold nanoparticles would be expected to bind oxygen more strongly [64] and thus have a more appropriate binding energy and higher activity, as it is also observed in graphite oxidation [91,92]. Among the tested materials, Co 3 O 4 and CeO 2 are the catalysts closest to the optimal oxygen bond strength.…”

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 99%

“…Figure 4 outlines the possible steps of the reaction mechanism. Reaction R1 is the broadly supported mechanism for adsorption of oxygen on a metal oxide [93][94][95] [91] proposal of a bridging metal-oxygen-carbon transition state lattice oxygen from the catalyst is then transferred to the carbonaceous material, in this case to form a semi-quinone species (R2). The reaction leaves a reduced surface site in the metal oxide, which is reoccupied according to R1.…”

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 99%

See 2 more Smart Citations

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Christensen

Grunwaldt

Jensen

2016

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

The oxygen bond strength on a catalyst, as measured by the heat of oxygen chemisorption, is observed to be a very important parameter for the activity of the catalyst in soot oxidation. With both intimate contact between soot and catalyst (tight contact) and with the solids stirred loosely together (loose contact) the rate constants for a number of catalytic materials outline a volcano curve when plotted against their heats of oxygen chemisorption. However, the optima of the volcanoes correspond to different heats of chemisorption for the two contact situations. In both cases the activation energies for soot oxidation follow linear Brønsted-Evans-Polanyi relationships with the heat of oxygen chemisorption. Among the tested metal or metal oxide catalysts Co 3 O 4 and CeO 2 were nearest to the optimal bond strength in tight contact oxidation, while Cr 2 O 3 was nearest to the optimum in loose contact oxidation. The optimum of the volcano curve in loose contact is estimated to occur between the bond strengths of α-Fe 2 O 3 and α-Cr 2 O 3 . Guided by an interpolation principle Fe a Cr b O x binary oxides were tested, and the activity of these oxides was observed to pass through an optimum for an FeCr 2 O x binary oxide catalyst, which exhibited a rate constant at 550 °C that was 2.3 times higher than the one for pure α-Cr 2 O 3 and 29 times higher than the one for pure α-Fe 2 O 3 .

show abstract

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 95%

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 99%

Section: Catalytic Oxidation In Tight Contactmentioning

confidence: 99%

See 1 more Smart Citation

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Christensen

Grunwaldt

Jensen

2016

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

show abstract

“…Previous studies in literature have shown that the oxidation of graphite single crystals can be effectively catalyzed by a two-step mechanism involving the mobility of metallic nanoparticles [43,44]. At 500 °C in a 670 Pa O2 atmosphere, platinum nanoparticles were reported to initially penetrate the graphite basal plane to produce pits.…”

Section: Origin Of Silver Mobility and Its Implications On Catalytic mentioning

confidence: 99%

“…This channeling effect could be explained by taking the adhesion energy between the metal particle and the carbon edge atoms in contact with it into consideration. This adhesion has been ascribed to van der Waal forces at the metal/carbon interface [44], although chemical bonding cannot be completely excluded. In DFT calculations Pizzocchero et al [46] did observe a bonding between the edge of graphene and silver.…”

Section: Origin Of Silver Mobility and Its Implications On Catalytic mentioning

confidence: 99%

Visualizing the mobility of silver during catalytic soot oxidation

Gardini

Christensen

Damsgaard

et al. 2016

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation temperature was significantly lower compared to uncatalyzed soot oxidation with soot and silver loosely stirred together (loose contact) and lowered further with the two components crushed together (tight contact). The in situ TEM investigations revealed that the silver particles exhibited significant mobility during the soot oxidation, and this mobility, which increases the soot/catalyst contact, is expected to be an important factor for the lower oxidation temperature. In the intimate tight contact mixture the initial dispersion of the silver particles is greater, and the onset of mobility occurs at a lower temperature which is consistent with the lower oxidation temperature of the tight contact mixture.

show abstract

Carbon

1996

Handbook of Microscopy Set

View full text Add to dashboard Cite

Catalytic oxidation of graphite

Cited by 98 publications

References 4 publications

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Visualizing the mobility of silver during catalytic soot oxidation

Carbon

Contact Info

Product

Resources

About